• Korean Journal of Medicinal Crop Science
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• v.21 no.2
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• pp.105-111
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• 2013

This study was performed to investigate the enhancement of immunomodulatory activities of Lithospermum erythrorhizon by extreme process. The extracts are WE100 (water extract for 24 hours at $100^{\circ}C$), WE80 (water extract for 24 hours at $80^{\circ}C$), EE (70% ethyl alcohol extract for 24 hours at $80^{\circ}C$) and EPE (extreme process for 30 minutes at $25^{\circ}C$, 500 MPa after 70% ethyl alcohol extracts for 3 hours at 40, 50, $60^{\circ}C$). Extraction yield was increased up to 5~10% by extreme process, compare to the normal extraction such as water solvent extraction, 70% ethyl alcohol solvent extraction. The cytotoxicity of the extracts was showed in the range of 12.68~15.89% at $1.0mg/m{\ell}$ for human lung cell (HEL299). The EPE40 was showed the lowest cytotoxicity 12.68%. The EPE60 extracted by extreme process increased the growth of human B and T cells up to $12.12{\times}10^4\;cells/m{\ell}$ and $14.88{\times}10^4\;cells/m{\ell}$, respectively and the EPE60 greatly increased the cytokine secretion of both IL-6 and TNF-${\alpha}$. The extracts by extreme process also exhibited higher levels of nitric oxide production from macrophages than the lipopolysaccaharides. It can be concluded that Lithospermum erythrorhizon has immune activities and The extreme process could increase higher immune activities possibly by immunomodulatory compounds.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.103-108
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• 2019

The cooling rate and the uniformity of mold temperature, in the injection molding process, possess great influences on the productivity and quality of replications. The conformal cooling channel, which is of a uniform spacing from the mold cavity by the metal additive manufacturing process, receives much attention recently. The purpose of this study is to develop a mold core with a curved conformal cooling channel for a pottery-shaped thick-wall cosmetic container through the hybrid method of direct metal tooling (DMT) process. In this study, we design a mold core that contains the curved cooling channel for the container. A method that divides the cavity is proposed and the DMT process is carried out to form the curved cooling channel. The test mold core, with the curved conformal cooling channel, has been fabricated by the proposed method to confirm the feasibility of the design concept. We show that no leakage is observed for the additive manufactured test mold core, and its physical properties demonstrate that it can be sufficiently used as the injection mold core.

• Communications for Statistical Applications and Methods
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• v.15 no.5
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• pp.793-798
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• 2008

Extreme value inference deals with fitting the generalized extreme value distribution model and the generalized Pareto distribution model, which are recently combined to give a single model, namely a two-dimensional non-homogeneous Poisson exceedance point process model. In this paper, we extend the two-dimensional non-homogeneous Poisson process model to include non-stationary effect or dependence on covariates and then derive the likelihood for the extended model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.258-261
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• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1351-1359
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• 2003

Extreme programming is the most representative methodology among agile software development methodologies which is agile in business environment which change fast. As software industry is matured, usability of software quality characteristics is emphasized gradually, but effort to obtain usability in extreme programming is insufficient. To improve usability of extreme programming, in this thesis, a software life cycle is defined by six phase as exploration, planning, iterations to release, productionizing, maintenance, and death phase. In this thesis, an extreme programming process which can improve usability is proposed by definition of 11 activities including integration testing and acceptance testing for usability testing, The proposed process is validated with four aspects. The proposed process is enhanced to support acceptance testing activity. The proposed extreme programming process is able to support CMM level 4 and quality assurance practice of CMM.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.83-88
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• 2018

Additive manufacturing (AM) technologies have attracted wide attention as key technologies for the next industrial revolution. Among AM technologies using various materials, powder bed fusion (PBF) processes and direct energy deposition (DED) are representative of the metal 3-D printing process. Both of these processes have a common feature that the laser is used as a heat source to fabricate the 3-D shape through melting of the metal powder and solidification. However, the material properties of the deposited metals differ when produced by different process conditions and methods. 17-4 precipitation-hardening stainless steel (17-4PH SS) is widely used in the field of aircraft, chemical, and nuclear industries because of its good mechanical properties and excellent corrosion resistance. In this study, we investigated the differences in microstructure and mechanical properties of deposited 17-4PH SS by PBF and DED processes, including the heat treatment effect.

• Communications for Statistical Applications and Methods
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• v.16 no.5
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• pp.803-812
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• 2009

The application of extreme value theory to financial data is a fairly recent innovation. The classical annual maximum method is to fit the generalized extreme value distribution to the annual maxima of a data series. An alterative modern method, the so-called threshold method, is to fit the generalized Pareto distribution to the excesses over a high threshold from the data series. A more substantial variant is to take the point-process viewpoint of high-level exceedances. That is, the exceedance times and excess values of a high threshold are viewed as a two-dimensional point process whose limiting form is a non-homogeneous Poisson process. In this paper, we apply the two-dimensional non-homogeneous Poisson process model to daily losses, daily negative log-returns, in the data series of KBW/USD exchange rate, collected from January 4th, 1982 until December 31 st, 2008. The main question is how to estimate extreme quantiles of losses such as the 10-year or 50-year return level.

• Ocean Systems Engineering
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• v.4 no.4
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• pp.293-308
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• 2014

Unlike the traditional displacement type vessels, the high speed planing crafts are supported by the lift forces which are highly non-linear. This non-linear phenomenon causes their motions in an irregular seaway to be non-Gaussian. In general, it may not be possible to express the probability distribution of such processes by an analytical formula. Also the process might not be stationary or ergodic in which case the statistical behavior of the motion to be constantly changing with time. Therefore the extreme values of such a process can no longer be calculated using the analytical formulae applicable to Gaussian processes. Since closed form analytical solutions do not exist, recourse is taken to fitting a distribution to the data and estimating the statistical properties of the process from this fitted probability distribution. The peaks over threshold analysis and fitting of the Generalized Pareto Distribution are explored in this paper as an alternative to Weibull, Generalized Gamma and Rayleigh distributions in predicting the short term extreme value of a random process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.89-94
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• 2018

Due to industrial advancement and environmental concerns, there is a demand for light-weight material parts with high-performance characteristics. In order to meet this demand, various studies have been conducted on developing high-performance castings to achieve composite features by coating only specific parts that require high performance, with dissimilar joining, rather than coating the entire material part. This study analyzed the possibility of forming a local composite layer on an aluminum alloy through evaporation pattern casting, and the effects of parameters on the aluminum alloy.

• Tribology and Lubricants
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• v.35 no.6
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• pp.362-368
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• 2019

In this study, mechanical and tribological properties were investigated by varying the process temperature (50, 100, 125 and 150℃) to reduce internal stress. The internal stress reduction by thermal dissociation ta-C coating film with increasing temperature is confirmed through the curvature radius of the ta-C coating according to the temperature of the SUS plate. As the coating temperature increased, the mechanical properties (hardness, modulus, toughness) deteriorated, which is in agreement with the Raman analysis results. As the temperature increased, the sp² phase ratio increased owing to the dissociation of the sp³ phase. The friction and wear properties are related to the process temperature during ta-C coating. Low friction and wear properties are observed in high hardness samples manufactured at 50℃, and wear resistance properties decreased with increasing temperature. The contact area is expected to increase owing to the decrease of hardness(72 GPa to 39 GPa) and fracture toughness with increasing temperature which accelerated wear because of the debris generated. It was confirmed that at process temperature of over than 100℃, the bond structure of the carbon film changed, and the effect of excellent internal stress was reduced. However, the wear resistance simultaneously decreased owing to the reduction in fracture toughness. Therefore, in order to increase industrial utilization, optimum temperature conditions that reduce internal stress and retain mechanical properties.